Stop self harming. See a therapist.
I have a ton of regret for how I treated my husband during our marriage. I didn't cheat on him, but I was pretty unaffectionate, unloving and unsupportive so now that he has begun our separation by moving out and "dating" other women, I'm left sitting here in our house with so much regret, newly found love for him (don't know what you got til it's gone), loneliness and depression and it is overwhelming.
I started seeing a counselor and it's helping a little, really journaling all of my feelings gets it out for a short time and I've gotten on an anti depressant just lately. I don't have much advice on how to move forward because I haven't been able to do that yet either, but self reflecting on your issues and what you need to change about you, making the best amends that you can to your spouse, unselfishly has helped me feel that I'm becoming a better person. Too late for my relationship though. I, like you have a tiny support network of my family, but no real friends to help me. I was always a loner and like it that way until now. Find a support group for separation/divorce in your area. I start one this week. Good luck

You need to speak to a therapist immediately. You need a safe outlet. People make mistakes, mistakes have consequences but you need to face them and start rebuilding your life. A therapist can help you. Also antidepressants